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+--- Thread: speedo 85 or 120 (/showthread.php?tid=1747)
speedo 85 or 120 - larsalan - 09-16-2010
What is the significance of the different top speeds?
My 300d turbo is 85 mph top but I have seen others that are 120mph.
is it the year or what?
RE: speedo 85 or 120 - Captain America - 09-16-2010
I think it's the year. Mine is the same as yours... Wish I had the 120 speedo (with the right calibration for my tires).
RE: speedo 85 or 120 - willbhere4u - 09-16-2010
I put the 120mph in my 1982 300cd it was of by like 5mph but it felt a lot slower at least the needle moves slower
With the 85mph it moves so quickly when you are getting on it lol
RE: speedo 85 or 120 - Captain America - 09-17-2010
So it would be a straight swap then?
RE: speedo 85 or 120 - DeliveryValve - 09-17-2010
(09-16-2010, 10:33 PM)larsalan What is the significance of the different top speeds?
My 300d turbo is 85 mph top but I have seen others that are 120mph.
is it the year or what?
There are no differences between the performance of the turbo models with the different speedometers.
In late 1979 the Federal lawmakers decided that the speedometers should have a maximin speed of 85 mph for efficiency and safety reasons. Then in late '81 the law was lifted because they found it to unlikely to provide any benefits. For an upgrade to a 120 mph speedo, you will need one off a car with a 3.07 differential - 1983 and 1984 model years only.
.
(09-16-2010, 11:29 PM)Captain America I think it's the year. Mine is the same as yours... Wish I had the 120 speedo (with the right calibration for my tires).
I would try to see if the speedometer off your '85 parts car would be close accurate with the tires you have. The '85 speedometers are calibrated for a 2.88 ratio differential.
RE: speedo 85 or 120 - Captain America - 09-17-2010
(09-17-2010, 12:06 PM)DeliveryValve(09-16-2010, 10:33 PM)larsalan What is the significance of the different top speeds?
My 300d turbo is 85 mph top but I have seen others that are 120mph.
is it the year or what?
There are no differences between the performance of the turbo models with the different speedometers.
In late 1979 the Federal lawmakers decided that the speedometers should have a maximin speed of 85 mph for efficiency and safety reasons. Then in late '81 the law was lifted because they found it to unlikely to provide any benefits. For an upgrade to a 120 mph speedo, you will need one off a car with a 3.07 differential - 1983 and 1984 model years only.
.
(09-16-2010, 11:29 PM)Captain America I think it's the year. Mine is the same as yours... Wish I had the 120 speedo (with the right calibration for my tires).
I would try to see if the speedometer off your '85 parts car would be close accurate with the tires you have. The '85 speedometers are calibrated for a 2.88 ratio differential.
Your the fuckin man! I never even thought of that... looks like it will work perfect. I think I applied this right, just had to put the numbers in backwards...
RE: speedo 85 or 120 - garage - 09-17-2010
(09-17-2010, 12:06 PM)DeliveryValve In late 1979 the Federal lawmakers decided that the speedometers should have a maximin speed of 85 mph for efficiency and safety reasons. Then in late '81 the law was lifted because they found it to unlikely to provide any benefits.
My 1979 240D has a 100mph speedo.
RE: speedo 85 or 120 - DeliveryValve - 09-17-2010
(09-17-2010, 08:51 PM)garage(09-17-2010, 12:06 PM)DeliveryValve In late 1979 the Federal lawmakers decided that the speedometers should have a maximin speed of 85 mph for efficiency and safety reasons. Then in late '81 the law was lifted because they found it to unlikely to provide any benefits.
My 1979 240D has a 100mph speedo.
Yes model year 1980 enacted the change, too late for '79 model year and again too late for the upcoming 1982 model year to make the change in late '81.
RE: speedo 85 or 120 - garage - 09-17-2010
Ahh i see.
Well thats nice information
RE: speedo 85 or 120 - winmutt - 09-20-2010
The 85 120mph speedo is different of course.
RE: speedo 85 or 120 - Rudolf_Diesel - 09-20-2010
My speedo was originally an 85 MPH, I got a 120 and replaced the gears and rolled it forward to match the 85 MPH odometer. I think it works fine since it is an electric speedo, those "Your Speed is XX" signs seem to be right on with my speedo, it might be off by a negligible amount. It also has a flat, velvety finish vs. the original satin finish. The tach wouldn't work from the new cluster so I had to use the old one.